Toward an Objective Characterization of an Anhedonic Phenotype: A Signal-Detection Approach
Diego A. Pizzagalli, Allison L. Jahn, and James P. O’Shea
Background: Difficulties in defining and characterizing phenotypes has hindered progress in psychiatric genetics and clinical
neuroscience. Decreased approach-related behavior and anhedonia (lack of responsiveness to pleasure) are considered cardinal
features of depression, but few studies have used laboratory-based measures to objectively characterize these constructs.
Methods: To assess hedonic capacity in relation to depressive, particularly anhedonic, symptoms, 62 participants completed a
signal-detection task based on a differential reinforcement schedule. Anhedonia was operationalized as decreased reward
Results: Unequal frequency of reward between two correct responses produced a response bias (i.e., a systematic preference to identify
the stimulus paired with the more frequent reward). Subjects with elevated depressive symptoms (Beck Depression Inventory scores
> 16) failed to show a response bias. Impaired reward responsiveness predicted higher anhedonic symptoms 1 month later, after
controlling for general negative affectivity.
Conclusions: Impaired tendency to modulate behavior as a function of prior reinforcement might underline diminished hedonic
capacity in depression. When applied to a clinical population, objective assessments of participants’ propensity to modulate behavior
as a function of reward might provide a powerful tool for improving the phenotypic definition of depression and thus offer a reliable
behavioral screening approach for neuroscience studies of depression.
Mean response bias for
subjects with high (black bars; n=15) and low (light gray bars; n=21) Beck
Depression Inventory (BDI) scores. Error bars represent standard errors.